A driver traveling on mountain or downhill roads mainly uses the engine brake to prevent rupture caused by brake pad bubbles. This is not economical because it consumes energy while decelerating. Accordingly, if a part of energy wasted in decelerating the bike is recovered and used as energy for various devices provided in the bike, the energy efficiency may be increased. However, conventionally bikes have no device for improving the energy efficiency.
An auxiliary wheel device for a two-wheeled vehicle disclosed in Korean Patent Application Publication No. 10-2014-0030005 is capable of preventing the vehicle from falling over and improving travel stability. The auxiliary wheel device includes a damping unit connecting a body of the two-wheeled vehicle to an auxiliary wheel and providing a damping force for attenuating impact that would otherwise be transmitted to the body through the auxiliary wheel, and a blocking unit selectively blocking the operation of the damping unit by an external operation of a user, wherein the user is allowed to selectively operate the damping unit through the external operation according to a driving condition
However, as the bike cannot stay balanced when stopped, the auxiliary wheel device for the two-wheeled vehicle is considered a limited technology that does not exhibit a remarkably improved technical effect compared to a stand that supports the bike. Even if this technology is applied, it may fail to maintain the bike at the upright position due to unevenness of the ground and strong force applied to the left side or right side of the bike, or the inconvenience caused to the bike riders by this technology may be greater than convenience provided to the bike riders when mounted on the bike. Further, when an unexpected strong shock is applied to the auxiliary wheels or the auxiliary wheels hit a relatively large obstacle, there is a risk that the bike will be overturned by the shock applied to the auxiliary wheels.
In the case of the automatic motor-driven stand apparatus having auxiliary wheels for safe driving assistance of a two-wheeled vehicle disclosed in Korean Patent Application Publication No. 10-2010-0134988, when the two-wheel vehicle enters a low-speed driving mode, in which it is difficult to balance the body of the two-wheeled vehicle, the auxiliary wheels are unfolded to aid in safe driving while maintaining the upright position of the body. In addition, the auxiliary wheels are designed to enhance stability in balancing the body when the two-wheeled vehicle travels along a road which is inclined to the left or right. To this end, the stand apparatus is arranged to support two points at both sides of a wheel of the two-wheeled vehicle and includes left and right auxiliary wheels rotatably mounted to support the two points. The left and right auxiliary wheels are automatically operated to contact the ground and support the body in an upright position when the vehicle speed is lower than a set vehicle speed and are controlled to be automatically folded to a horizontal position when the vehicle speed is higher than the set vehicle speed.
However, even this technology may fail to maintain the bike in the upright position due to unevenness of the ground and strong unbalancing force applied to the left side or right side of the bike or may cause inconvenience to the bike riders. In particular, when an unexpected strong shock is applied to the left and right auxiliary wheels or the auxiliary wheels hit a relatively large obstacle, there is a risk that the two-wheeled vehicle will be overturned by the shock applied to the auxiliary wheels. In addition, when the left side and the right side of the ground are at different heights, the auxiliary wheels must be individually supported on the ground according to the difference in height. This operation solely depends on the springs while the auxiliary wheels are driven at the same height in the forward and reverse directions simultaneously by using a wire and a transport means. Even if the auxiliary wheels are operated during travel, the horizontally balanced bike may become significantly unstable due to imbalance between the left and right sides of the ground. In other words, this technology fails to resolve lateral imbalance, and may require spring tension control to maintain balance. However, a variable spring tension mechanism may result in excess complexity and the document only discloses that the auxiliary wheels are raised when the inclination is inappropriate. If the auxiliary wheels are raised in this way, a motorcycle may be overturned immediately.
Korean Patent Application Publication No. 10-2013-0127718 discloses an auxiliary wheel device for a bike capable of effectively absorbing impact to provide stable ride comfort and to improve driving stability. The auxiliary wheel device includes an auxiliary wheel portion rotatably connected to the body of the bike, a shock absorbing portion for attenuating impact applied to the body of the bike via the auxiliary wheel portion, and a stopper portion for temporarily restricting rotation of the auxiliary wheel portion with respect to the body of the bike, wherein the restriction imposed by the stopper portion is released and the auxiliary wheel portion rotates with respect to the body of the bike when an impact greater than the impact that the shock absorbing portion can bear is applied to the auxiliary wheel portion.
However, the disclosed technology is merely a small and simple mechanism that is used to sense or check the length and height of a product on a small conveyor belt or a counter. The disclosed technology needs to be improved to support a greatly varying load for balancing the bike and to be applied to a vehicle which moves over uneven terrain and undergoes large impact from the ground during travel. The basic design frame of this technology is not suitable for a bike whose center of gravity severely shifts laterally and which is very likely to be laterally inclined with an excessive load. Further, the technology fails to secure stability against change of the ground without hindering open autonomy of the rider's driving.
Although the two-wheeled bike provides open driving autonomy and better maneuverability compared to the four-wheeled vehicle and thus exposes the riders to many risks, bike lovers are growing in number. Due to the nature of bikes, bikes require a lot of technologies to achieve the inherent purpose of mounting the auxiliary wheels while meeting mobility and flexibility and securing better safety. However, the conventional auxiliary wheel apparatuses may impose restrictions on the bike rider's autonomy or have no remarkable improvement except the function of assisting and supporting the conventional stand. Although there are some advanced technologies, they are not preferred by the bike riders as they are not sufficiently controlled in response to independent lateral change in angle.